A Novel Drug-Drug Cocrystal of Levofloxacin and Metacetamol: Reduced Hygroscopicity and Improved Photostability of Levofloxacin

Pharmaceutical cocrystals: a rising star in drug delivery applications

Pharmaceutical cocrystals, owing to their manifold applications, are acting as bridge between drug discovery and pharmaceutical product development. The ability to scale up pharmaceutical cocrystals through continuous manufacturing approaches offers superior and economic pharmaceutical products. Moreover, cocrystals can be an aid for the nanoparticulate systems to solve the issues related to scale-up and cost. Cocrystals grabbed attention of academic researchers and pharmaceutical scientist due to their potential to target various diseases like cancer. The present review is mainly focussed on the diverse and comprehensive applications of pharmaceutical cocrystals in drug delivery including solubility and dissolution enhancement, improvement of bioavailability of drug, mechanical and flow properties of active pharmaceutical ingredients, controlled/sustained release and colour tuning of API. Besides, phytochemical based cocrystals, multi-drug cocrystals and cocrystals for tumour therapy have been discussed in this review. Additionally, recent progress pertinent to pharmaceutical cocrystals is also included, which may provide future directions to manufacturing and scale-up of cocrystals.

New Cocrystals of Ligustrazine: Enhancing Hygroscopicity and Stability

Ligustrazine (TMP) is the main active ingredient extracted from Rhizoma Chuanxiong, which is used in the treatment of cardiovascular and cerebrovascular diseases, with the drawback of being unstable and readily sublimated. Cocrystal technology is an effective method to improve the stability of TMP. Three benzoic acid compounds including P-aminobenzoic acid (PABA), 3-Aminobenzoic acid (MABA), and 3,5-Dinitrobenzoic acid (DNBA) were chosen for co-crystallization with TMP. Three novel cocrystals were obtained, including TMP-PABA (1:2), TMP-MABA (1.5:1), and TMP-DNBA (0.5:1). Hygroscopicity was characterized by the dynamic vapor sorption (DVS) method. Three cocrystals significantly improved the hygroscopicity stability, and the mass change in TMP decreased from 25% to 1.64% (TMP-PABA), 0.12% (TMP-MABA), and 0.03% (TMP-DNBA) at 90% relative humidity. The melting points of the three cocrystals were all higher than TMP, among which the TMP-DNBA cocrystal had the highest melting point and showed the best stability in reducing hygroscopicity. Crystal structure analysis shows that the mesh-like structure formed by the O-H⋯N hydrogen bond in the TMP-DNBA cocrystal was the reason for improving the stability of TMP.

An analysis of multidrug multicomponent crystals as tools for drug development

In a typical tablet or capsule formulation, the active drug is often present as a crystalline solid. This solid emerges from the relationships between the individual atoms within the crystal, which confer a distinct set of physical properties. Then, it follows that if we modify the packing arrangement of the individual molecules within these crystals, we can modulate their properties. This can be achieved by crystal engineering. Crystal engineering has also seen teams arrange multiple drug molecules within the same crystal, resulting in dramatic improvements to drug properties in the lab. The success of drugs like SEGLENTIS® and Entresto® have revitalised interest in these forms, but controversy surrounding their translation has prompted this reconsideration of their clinical utility. I reflect on the current academic, clinical, and commercial interest in multidrug multicomponent crystals, drawing parallels with developments pre-Bragg, contributing to a nuanced understanding of the potential and limitations of crystal engineering in pharmaceutical applications.

In-Silico Aided Screening and Characterization Results in Stability Enhanced Novel Roxadustat Co-Crystal

Roxadustat (RXD) is an approved drug substances for the treatment of renal anemia. It has poor aqueous solubility and photochemical stability. This study employs a comprehensive approach to enhance the stability and physicochemical properties RXD through coformer selection and characterization. The investigation integrates delta pKa analysis, molecular complementary assessment, molecular electrostatic potential surface analysis, and machine learning techniques to predict potential co-crystal formation and binding interactions between drug molecules and coformers. The co-crystal screening which lead to in a novel RXD-nicotinamide co-crystal (RXD-NA). Experimental characterization underscores the physical and chemical stability of the co-crystals. To elucidate the supramolecular synthons and understand the intermolecular interactions in the RXD-NA co-crystal, Hirshfeld surfaces analysis, quantum theory of atoms in molecules (QTAIM) analysis and non-covalent interaction (NCI) analysis were performed. Computational analysis of photo-isomer formation aligns with experimental observations, further enhancing our understanding of RXD-coformer interactions. RXD-NA co-crystal was found photo-chemically stable as compared to free base API drug substance. This integrated methodology provides a systematic framework for informed co-crystal design, holding promise for optimizing RXD formulations based on molecular interactions and stability considerations. Consequently, this study contributes valuable insights to the field of rational drug design and formulation optimization.

A Population Pharmacokinetic Study to Compare a Novel Empagliflozin L-Proline Formulation with Its Conventional Formulation in Healthy Subjects

Empagliflozin is a sodium-glucose cotransporter 2 (SGLT2) inhibitor that is commonly used for the treatment of type 2 diabetes mellitus (T2DM). CKD-370 was newly developed as a cocrystal formulation of empagliflozin with co-former L-proline, which has been confirmed to be bioequivalent in South Korea. This study aimed to quantify the differences in the absorption phase and pharmacokinetic (PK) parameters of two empagliflozin formulations in healthy subjects by using population PK analysis. The plasma concentration data of empagliflozin were obtained from two randomized, open-label, crossover, phase 1 clinical studies in healthy Korean subjects after a single-dose administration. A population PK model was constructed by using a nonlinear mixed-effects (NLME) approach (Monolix Suite 2021R1). Interindividual variability (IIV) and interoccasion variability (IOV) were investigated. The final model was evaluated by goodness-of-fit (GOF) diagnostic plots, visual predictive checks (VPCs), prediction errors, and bootstrapping. The PK of empagliflozin was adequately described with a two-compartment combined transit compartment model with first-order absorption and elimination. Log-transformed body weight significantly influenced systemic clearance (CL) and the volume of distribution in the peripheral compartment (V2) of empagliflozin. GOF plots, VPCs, prediction errors, and the bootstrapping of the final model suggested that the proposed model was adequate and robust, with good precision at different dose strengths. The cocrystal form did not affect the absorption phase of the drug, and the PK parameters were not affected by the different treatments.

Essential considerations towards development of effective nasal antibiotic formulation: features, strategies, and future directions

INTRODUCTION

Intranasal antibiotic products are gaining popularity as a promising method of administering antibiotics, which provide numerous benefits, e.g. enhancing drug bioavailability, reducing adverse effects, and potentially minimizing resistance threats. However, some issues related to the antibiotic substances and nasal route challenges must be addressed to prepare effective formulations.

AREAS COVERED

This review focuses on the valuable points of nasal delivery as an alternative route for administering antibiotics, coupled with the challenges in the nasal cavity that might affect the formulations. Moreover, this review also highlights the application of nasal delivery to introduce antibiotics for local therapy, brain targeting, and systemic effects that have been conducted. In addition, this viewpoint provides strategies to maintain antibiotic stability and several crucial aspects to be considered for enabling effective nasal formulation.

EXPERT OPINION

In-depth knowledge and understanding regarding various key considerations with respect to the antibiotic substances and nasal route delivery requirement in preparing effective nasal antibiotic formulation would greatly improve the development of nasally administered antibiotic products, enabling better therapeutic outcomes of antibiotic treatment and establishing appropriate use of antibiotics, which in turn might reduce the chance of antibiotic resistance and enhance patient comfort.

Tuning Caco-2 permeability by cocrystallization: Insights from molecular dynamics simulation

Emerging evidence suggests that intestinal permeability can be potentially enhanced through cocrystallization. However, a mechanism for this effect remains to be established. In this study, we first demonstrate the enhancement in intestinal permeability, evaluated by the Caco-2 cell permeability assay, of acetazolamide (ACZ) in the presence of a conformer, p-aminobenzoic acid (PABA), delivered in the form of a 1:1 cocrystal. The binding strength of ACZ and PABA with the Pgp efflux transporter, either alone or as a mixture, was calculated using molecular dynamics simulation. Results show that PABA weakens the binding of ACZ with Pgp, which leads to a lower efflux ratio and elevated permeability of ACZ. This work provides molecular-level insights into a potentially effective strategy to improve the intestinal permeability of drugs. If the same cocrystal also exhibits higher solubility, oral bioavailability of BCS IV drugs can likely be improved by forming a cocrystal with a Pgp inhibitor.

Molecular complexes of drug combinations: A review of cocrystals, salts, coamorphous systems and amorphous solid dispersions

As the advancements in the medical technology and healthcare develop through the years, combinational therapy has evolved to be an important treatment modality in many disease settings, including cancer, cardiovascular disease and infectious diseases. In an effort to alleviate "pill burden" and improve patient compliance, fixed dose combinations (FDCs) have been developed to be used as effective therapeutics. Among all FDCs, the category of drug-drug molecular complexes has been proven an efficient methodology in designing and treating diseases, with many drugs being approved. Among all drug-drug molecular complexes, drug-drug cocrystals, salts, coamorphous systems and solid dispersions have been successfully developed and many have been approved by the FDA. In this review, we dwell deeply into the molecular mechanisms behind the different types of drug-drug molecular complexes, including the key functional groups involved in the intermolecular interactions, the applications of each category of molecular complexes, as well as the advantages and challenges thereof. This comprehensive review provides useful insights into the practical design and manufacture of drug-drug molecular complexes and points out the future direction for the development of new advantageous combinational therapies that benefit more patients.

Comparison of the Pharmacokinetics, Safety, and Tolerability of Two Empagliflozin Formulations in Healthy Korean Subjects

Purpose

Empagliflozin is a sodium-glucose cotransporter 2 inhibitor that is commonly used for the treatment of type 2 diabetes mellitus. As cocrystal formulation can improve the chemical properties of drugs, CKD-370 was newly developed as a cocrystal formulation of empagliflozin with solvate L-proline. This study aimed to compare the pharmacokinetics, safety, and tolerability of these two empagliflozin formulations in healthy Korean subjects.

Methods

A randomized, open-label, two-sequence, two-period crossover study was conducted on healthy Korean participants. The subjects received a single oral 25 mg dose of either test (CKD-370) or reference treatment (Jardiance^®) tablet at each period. Plasma empagliflozin concentrations were determined using liquid chromatography with tandem mass spectrometry. Pharmacokinetic (PK) parameters were analyzed using non-compartmental methods. The primary PK parameters included the maximum concentration (C_max) and the area under the concentration-time curve from 0 to last (AUC_last). The safety of both formulations was monitored and evaluated.

Results

A total of 28 healthy Korean adult subjects were randomized, and 27 subjects were included in the PK analysis. The mean ± standard deviation values of the primary PK parameters, C_max and AUC_last after administration of the test treatment, were 442.02 ± 103.37 μg/L and 3131.08 ± 529.30 μg·h/L, respectively, and those after administration of the reference treatment were 436.29 ± 118.74 μg/L and 3006.88 ± 514.21 μg·h/L, respectively. The geometric mean ratio and its 90% confidence interval of test to reference treatment for C_max and AUC_last were 1.0221 (0.9527-1.0967) and 1.0411 (1.0153-1.0677), respectively, which were within the commonly accepted bioequivalence criteria of 0.80 to 1.25. Both treatments were well-tolerated.

Conclusion

The two formulations of empagliflozin showed similar PK characteristics and were generally well tolerated in healthy subjects.

The Benefits and Challenges of Antibiotics-Non-Steroidal Anti-Inflammatory Drugs Non-Covalent Reaction

Recently, non-covalent reactions have emerged as approaches to improve the physicochemical properties of active pharmaceutical ingredients (API), including antibiotics and non-steroidal anti-inflammatory drugs (NSAIDs). This review aimed to present and discuss the non-covalent reaction products of antibiotics, including salt and neutral multi-component solid forms, by framing their substituents and molar ratios, manufacturing techniques, characterization methods, benefits, potency changes, and toxicity, and is completed with an analysis of the development of computational models used in this field. Based on the data, NSAIDs are the most-developed drugs in multi-component system preparations, followed by antibiotics, i.e., antituberculosis and fluoroquinolones. They have reacted with inorganic elements, excipients, nutraceuticals, natural products, and other drugs. However, in terms of treatments for common infections, fluoroquinolones are more frequently used. Generally, NSAIDs are acquired on an over-the-counter basis, causing inappropriate medication. In addition, the pKa differences between the two groups of medicine offer the potential for them to react non-covalently. Hence, this review highlights fluoroquinolone-NSAID multi-component solid systems, which offer some benefits. These systems can increase patient compliance and promote the appropriate monitoring of drug usage; the dual drug multi-component solids have been proven to improve the physicochemical properties of one or both components, especially in terms of solubility and stability. In addition, some reports show an enhancement of the antibiotic activity of the products. However, it is important to consider the possibility of activity changes, interaction, and toxicity when using drug combinations. Hence, these aspects also are discussed in this review. Finally, we present computational modeling, which has been utilized broadly to support multi-component system designs, including coformer screening, preparation methods, and structural modeling, as well as to predict physicochemical properties, potency, and toxicity. This integrated review is expected to be useful for further antibiotic-NSAID multi-component system development.

Mitigating Drug Stability Challenges Through Cocrystallization

Drug stability plays a significant role in the pharmaceutical industry from early-phase drug discovery to product registration as well as the entire life cycle of a product. Various formulation approaches have been employed to overcome drug stability issues. These approaches are sometimes time-consuming which ultimately affect the timeline of the product launch and may further require formulation optimization steps, affecting the overall cost. Pharmaceutical cocrystal is a well-established route to fine tune the biopharmaceutical properties of drugs without covalent modification. This article highlights the role of cocrystallization in mitigating the stability issues of challenging drug molecules. Representative case studies wherein the drug stability issue is addressed through pharmaceutical cocrystals have been discussed briefly and are summarized in tabular form. The emphasis has been made on the structural information of cocrystals and understanding the mechanism that improves the stability of the parent drug through cocrystallization. Besides, a guided strategy has been proposed to modulate the stability of drug molecules through cocrystallization approach. Finally, the stability concern of fixed-dose or drug combinations and the challenges associated with cocrystals are also touched.

Co-Crystallization Approach to Enhance the Stability of Moisture-Sensitive Drugs

Stability is an essential quality attribute of any pharmaceutical formulation. Poor stability can change the color and physical appearance of a drug, directly impacting the patient's perception. Unstable drug products may also face loss of active pharmaceutical ingredients (APIs) and degradation, making the medicine ineffective and toxic. Moisture content is known to be the leading cause of the degradation of nearly 50% of medicinal products, leading to impurities in solid dose formulations. The polarity of the atoms in an API and the surface chemistry of API particles majorly influence the affinity towards water molecules. Moisture induces chemical reactions, including free water that has also been identified as an important factor in determining drug product stability. Among the various approaches, crystal engineering and specifically co-crystals, have a proven ability to increase the stability of moisture-sensitive APIs. Other approaches, such as changing the salt form, can lead to solubility issues, thus making the co-crystal approach more suited to enhancing hygroscopic stability. There are many reported studies where co-crystals have exhibited reduced hygroscopicity compared to pure API, thereby improving the product's stability. In this review, the authors focus on recent updates and trends in these studies related to improving the hygroscopic stability of compounds, discuss the reasons behind the enhanced stability, and briefly discuss the screening of co-formers for moisture-sensitive drugs.

Stability and Antibiotic Potency Improvement of Levofloxacin by Producing New Salts with 2,6- and 3,5-Dihydroxybenzoic Acid and Their Comprehensive Structural Study

Recently, solid-state engineering has become a promising approach to improving the stability and potency of antibiotics. Levofloxacin (LF) is a broad-spectrum fluoroquinolone antibiotic marketed in solid and solution dosage forms. However, this substance forms solid hydrates under ambient conditions and degrades due to lighting, which may change its solid properties and dose. In addition, resistance cases have been reported due to long-time antibiotic usage. This research aims to allow LF to react with antioxidant dihydroxybenzoic acid (DHBA), which has low antimicrobial activity, to produce a more stable compound under water and lighting conditions and improve LF's potency. The experiment begins with a screening to select potential DHBA isomers that can react with LF and predict the stoichiometric ratio using phase diagrams, which show that 2,6-DHBA and 3,5-DHBA are prospective antioxidants that can react with LF in a (1:1) molar ratio. Multicomponent systems are prepared by dissolving the LF-DHBA mixture in (1:1) ethanol-methanol (95% grade) and evaporating it. Then, the new solid phase formation is confirmed by thermal analysis and powder X-ray diffractometry. Next, infrared spectrophotometry and neutron magnetic resonance analyses are used to identify the LF-DHBA's interactions. Finally, single-crystal X-ray diffractometry is used to solve the three-dimensional structure of the multicomponent system. We then conduct a hygroscopicity and stability test followed by a lighting and potency test using the microdilution method. Our data reveal that both reactions produce salts, which are named LF-26 and LF-35, respectively. Structurally, LF-26 is found in an anhydrous form with a triclinic crystal packing, while LF-35 is a hemihydrate in a monoclinic system. Afterward, both salts are proven more stable regarding water adsorption and UV lighting than LF. Finally, both multicomponent systems have an approximately two-fold higher antibiotic potency than LF. LF-26 and LF-35 are suitable for further development in solid and liquid dosage formulations, especially LF-35, which has superior stability compared with LF-26.

Strategic developments in the drug delivery of natural product dihydromyricetin: applications, prospects, and challenges

Dihydromyricetin (DHM) is an important natural flavonoid that has attracted much attention because of its various functions such as protecting the cardiovascular system and liver, treating cancer and neurodegenerative diseases, and anti-inflammation effect, etc. Despite its great development potential in pharmacy, DHM has some problems in pharmaceutical applications such as low solubility, permeability, and stability. To settle these issues, extensive research has been carried out on its physicochemical properties and dosage forms to produce all kinds of DHM preparations in the past ten years. In addition, the combined use of DHM with other drugs is a promising strategy to expand the application of DHM. However, although invention patents for DHM preparations have been issued in several countries, the current transformation of DHM research results into market products is insufficient. To date, there is still a lack of deep research into the pharmacokinetics, pharmacodynamics, toxicology, and action mechanism of DHM preparations. Besides, preparations for combined therapy of DHM with other drugs are scarcely reported, which necessitates the development of dosage forms for this application. Apart from medicine, the development of DHM in the food industry is also of great potential. Due to its multiple effects and excellent safety, DHM preparations can be developed for functional drinks and foods. Through this review, we hope to draw more attention to the development potential of DHM and the above challenges and provide valuable references for the research and development of other natural products with a similar structure-activity relationship to this drug.

Design, Preparation, Characterization and Evaluation of Five Cocrystal Hydrates of Fluconazole with Hydroxybenzoic Acids

To modulate the physicochemical properties of fluconazole (FLZ), a multifunctional antifungal drug, the crystal engineering technique was employed. In this paper, five novel cocrystal hydrates of FLZ with a range of phenolic acids from the GRAS list, namely, 2,4-dihydroxybenzoic acid (24DHB), 3,4-dihydroxybenzoic acid (34DHB, form I and form II), 3,5-dihydroxybenzoic acid (35DHB), and 3,4,5-trihydroxybenzoic acid (345THB) were disclosed and reported for the first time. Crystals of these five hydrates were all obtained for single-crystal X-ray diffraction (SCXRD) analysis. Robust (hydroxyl/carboxyl) O-H. . . N_arom hydrogen bonds between acids and FLZ triazolyl moiety were observed to be dominant in guiding these crystal forms. The water molecule plays the role of supramolecular "linkage" in the strengthening and stabilization of these hydrates by interacting with FLZ and acids through O-H. . . O hydrogen bonds. In particular, the formation of FLZ-34DHB-H₂O (1:1:1) significantly reduces hygroscopicity and hence improves the stability of FLZ, the latter of which is unstable and easily transforms into its monohydrate form. Increased initial dissolution rates were observed in the obtained cocrystal forms, and an enhanced intrinsic dissolution rate was obtained in FLZ-35DHB-H₂O (1:1:1) in comparison with commercialized FLZ form II.

Formulation Strategies to Improve the Stability and Handling of Oral Solid Dosage Forms of Highly Hygroscopic Pharmaceuticals and Nutraceuticals

Highly hygroscopic pharmaceutical and nutraceutical solids are prone to significant changes in their physicochemical properties due to chemical degradation and/or solid-state transition, resulting in adverse effects on their therapeutic performances and shelf life. Moisture absorption also leads to excessive wetting of the solids, causing their difficult handling during manufacturing. In this review, four formulation strategies that have been employed to tackle hygroscopicity issues in oral solid dosage forms of pharmaceuticals/nutraceuticals were discussed. The four strategies are (1) film coating, (2) encapsulation by spray drying or coacervation, (3) co-processing with excipients, and (4) crystal engineering by co-crystallization. Film coating and encapsulation work by acting as barriers between the hygroscopic active ingredients in the core and the environment, whereas co-processing with excipients works mainly by adding excipients that deflect moisture away from the active ingredients. Co-crystallization works by altering the crystal packing arrangements by introducing stabilizing co-formers. For hygroscopic pharmaceuticals, coating and co-crystallization are the most commonly employed strategies, whereas coating and encapsulation are popular for hygroscopic nutraceuticals (e.g., medicinal herbs, protein hydrolysates). Encapsulation is rarely applied on hygroscopic pharmaceuticals, just as co-crystallization is rarely used for hygroscopic nutraceuticals. Therefore, there is potential for improved hygroscopicity reduction by exploring beyond the traditionally used strategy.

Present Status, Challenges, and Prospects of Dihydromyricetin in the Battle against Cancer

Dihydromyricetin (DHM) is a natural flavonoid compound extracted from Ampelopsis grossedentata that has been used for centuries in traditional Chinese medicine. DHM has attracted intensive attention due to its numerous beneficial activities, such as hepatoprotection, cardioprotection, antioxidant, and anti-inflammation. In addition, DHM inhibits the progression of cancers such as lung cancer, hepatocellular cancer, breast cancer, melanoma, and malignant reproductive systems through multiple mechanisms, including antiangiogenesis, antiproliferation, apoptosis, and inhibition of invasion and migration. Notably, DHM also activates autophagy at different levels, exerting a dual-regulatory effect on cancers. Mechanistically, DHM can effectively regulate mammalian target of rapamycin (mTOR), noncoding RNA-mediated signaling, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway, nuclear factor-κB (NF-κB), p53, and endoplasmic reticulum stress (ER stress)-driven signaling in different types of cancers. DHM has also been shown to have inhibitory effects on various regulators that trigger epithelial–mesenchymal transition (EMT). Furthermore, DHM exhibits a remarkable anticancer reversal ability when used in combination with drugs such as adriamycin, nedaplatin, and other drugs. However, the low bioavailability of DHM limits its potential applications, which are improved through structural modification and the exploration of novel dosage forms. Therefore, DHM may become a promising candidate for treating malignancies alone or combined with conventional anticancer strategies used in clinical practice.

Cocrystals of tuberculosis antibiotics: Challenges and missed opportunities

Cocrystals have been extensively used to improve the physicochemical properties and bioavailability of active pharmaceutical ingredients. Cocrystals of anti-tuberculosis medications are among those commonly reported. This review provides a summary of the tuberculosis antibiotic cocrystals reported in the literature, providing the main results on current tuberculosis medications utilized in cocrystals. Moreover, anti-tuberculosis cocrystals limitations and advantages are described, including evidence for enhanced solubility, stability and effect. Opportunities to enhance anti-tuberculosis medications and fixed dose combinations using cocrystals are given. Several cocrystal pairs are suggested to enhance the effectiveness of anti-tuberculosis drugs.

Unlocking the potential of drug-drug cocrystals - A comprehensive review

Intensive research subjected to the improvement of solubility and bioavailability of certain drugs has popularized the formation of cocrystals, wherein the desired drug is non-ionically bonded to a coformer by means of weak bonds. This paper addresses how crystal engineering of two compatible drug components can enhance the physicochemical and therapeutic properties of either or both of the drugs, resulting in drug-drug cocrystals, with pertinent examples. The paper also discusses the continuous screening processes which are replacing the traditional methods of crystallization due to numerous benefits to the producer as well as the products. Although faced with certain regulatory and scale-up constraints, cocrystals provide immense opportunities to the field of novel drug development.

Levofloxacin Cocrystal/Salt with Phthalimide and Caffeic Acid as Promising Solid-State Approach to Improve Antimicrobial Efficiency

To overcome the issue of multidrug resistant (MDR) microbes, the exploration of ways to improve the antimicrobial efficiency of existing antibiotics is one of the promising approaches. In search of synthons with higher efficiency, in current investigations, cocrystal and amorphous salt of levofloxacin hemihydrate (LEV) were developed with phthalimide (PTH) and caffeic acid (CFA). New materials were characterized with the help of FT-IR, Raman spectroscopy, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Shifting, attenuation, appearance/disappearance and broadening of bands were observed in the FT-IR and Raman spectra of the materials as evidence of the required product. The PXRD diffraction pattern observed for LEV-PTH indicated cocrystal while halo diffractogram of LEV-CFA revealed amorphous nature. DSC/TG analysis confirmed the hydrated nature of the cocrystal/salt. The dissolution rate and antimicrobial activity against selected strains, K.pneumonia, E. coli and S. typhi of parent drug and the new material were compared. The zone of inhibition (ZI) observed for 5 µg LEV-PTH was 30.4 + 0.36 (K. pneumonia), 26.33 + 0.35 (E. coli) and 30.03 + 0.25 mm (S. typhi) while LEV-CFA salt (5 µg) against the same strains inhibited 33.96 ± 0.25, 31.66 ± 0.35 and 27.93 ± 0.40 mm, respectively. These novel formulations enhance the dissolution rate as well as antibacterial efficiency and are expected to be potent against MDR bacterial strains.

Solid-State and Particle Size Control of Pharmaceutical Cocrystals using Atomization-Based Techniques

Poor bioavailability and aqueous solubility represent a major constraint during the development of new API molecules and can influence the impact of new medicines or halt their approval to the market. Cocrystals offer a novel and competitive advantage over other conventional methods with respect towards the substantial improvement in solubility profiles relative to the single-API crystals. Furthermore, the production of such cocrystals through atomization-based methods allow for greater control, with respect to particle size reduction, to further increase the solubility of the API. Such atomization-based methods include supercritical fluid methods, conventional spray drying and electrohydrodynamic atomization/electrospraying. The influence of process parameters such as solution flow rates, pressure and solution concentration, in controlling the solid-state and final particle size are discussed in this review with respect to atomization-based methods. For the last decade, literature has been attempting to catch-up with new regulatory rulings regarding the classification of cocrystals, due in part to data sparsity. In recent years, there has been an increase in cocrystal publications, specifically employing atomization-based methods. This review considers the benefits to employing atomization-based methods for the generation of pharmaceutical cocrystals, examines the most recent regulatory changes regarding cocrystals and provides an outlook towards the future of this field.

New Organic Salt from Levofloxacin-Citric Acid: What Is the Impact on the Stability and Antibiotic Potency?

This research dealt with the composition, structure determination, stability, and antibiotic potency of a novel organic salt composed of levofloxacin (LF) and citric acid (CA), named levofloxacin-citrate (LC). After a stoichiometric proportion screening, the antibiotic-antioxidant reaction was conducted by slow and fast evaporation methods. A series of characterizations using thermal analysis, powder X-ray diffractometry, vibrational spectroscopy, and nuclear magnetic resonance confirmed LC formation. The new organic salt showed a distinct thermogram and diffractogram. Next, Fourier transform infrared indicated the change in N-methylamine and carboxylic stretching, confirmed by ¹H nuclear magnetic resonance spectra to elucidate the 2D structure. Finally, single-crystal diffractometry determined LC as a new salt structure three-dimensionally. The attributive improvements were demonstrated on the stability toward the humidity and lighting of LC compared to LF alone. Moreover, the antibiotic potency of LF against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) enhanced ~1.5–2-fold by LC. Hereafter, LC is a potential salt antibiotic-antioxidant combination for dosage formulas development.

Novel dapagliflozin di-L-proline cocrystal-loaded tablet: Preparation, physicochemical characterization, and pharmacokinetics in beagle dogs and mini-pigs

Dapagliflozin base and a commercial dapagliflozin propanediol hydrate cocrystal (DPF-PDHC) were highly hygroscopic and thermally unstable. In this study, to address this limitation, we prepared a novel dapagliflozin di-L-proline cocrystal (DPF-LPC) and evaluated its physicochemical characterization compared with DPF-PDHC. After the preparation of the DPF-LPC-loaded tablet, its dissolution, stability and bioequivalence in beagle dogs and mini-pigs were assessed. DPF-LPC was well prepared with a dapagliflozin base and L-proline in a molar ratio of 1:2. Similar to DPF-PDHC, DPF-LPC was highly lipophilic and crystalline in nature. However, these two cocrystals exhibited different melting points and crystalline structures, indicating their different cocrystal forms. Moreover, DPF-LPC exhibited less hygroscopicity and lower water content than DPF-PDHC. The DPF-LPC-loaded tablet composed of DPF-LPC, Comprecel M102, lactose monohydrate, crospovidone, magnesium stearate, and Opadry (coating) at a weight ratio of 15.6:104.4:100.0:8.0:2.0:7.0, was dissolution-equivalent to the commercial tablet. Moreover, it provided lower impurities than the commercial tablet, indicating its better stability. In the two animals, there were no significant differences in the plasma concentrations, AUC, C_max, and T_max values, suggesting that they were bioequivalent. Therefore, the novel DPF-LPC-loaded tablet with excellent stability and bioequivalence may be used as a potential alternative to the commercial DPF-PDHC-loaded tablet.

Compatibility of Drotaverine Hydrochloride with Ibuprofen and Ketoprofen Nonsteroidal Anti-Inflammatory Drugs Mixtures

Formulations with two or more active pharmaceutical ingredients (APIs) are a researched trend due to their convenient use compared with multiple medications. Moreover, drug-drug combinations may have a synergistic effect. Drotaverine hydrochloride (D-HCl) is commonly used for its antispasmodic action. The combination of a spasmolytic and an analgesic drug such as ibuprofen (Ibu) or ketoprofen (Ket) could become the answer for the treatment of localized pain. D-HCl:Ibu and D-HCl:Ket drug-drug interactions leading to the formation of eutectic compositions with increased bioavailability, obtained by mechanosynthesis, a green, solvent-free method was explored for the first time. The compatibility of Ibuprofen, Ketoprofen, and Drotaverine Hydrochloride was investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier-Transform Infrared spectroscopy (FTIR). Solid-liquid equilibrium (SLE) phase diagrams for the binary systems of active pharmaceutical ingredients were developed and the Tammann diagrams were designed to determine the eutectic compositions. The excess thermodynamic functions G^E for the pre-, post-, and eutectic compositions were obtained using the computed activity coefficients data. Results show that drotaverine-based pharmaceutical forms for pain treatment may be obtained at 0.9 respectively 0.8 molar fractions of ibuprofen and ketoprofen which is advantageous because the maximum allowed daily dose of Ibu is about 6 times higher than those of D-HCl and Ket. The obtained eutectics may be a viable option for the treatment of pain associated with cancer therapy.

Computational approach to elucidate the formation and stabilization mechanism of amorphous formulation using molecular dynamics simulation and fragment molecular orbital calculation

α-Glycosyl rutin (Rutin-G) consists of a flavonol skeleton and sugar groups and is a promising additive for amorphous formulations. In our previous study, experimental approaches suggested an interaction between the model drug carbamazepine (CBZ) and flavonol skeleton of Rutin-G that stabilizes amorphous formulations. In the present study, the formation and stabilization mechanisms of CBZ/Rutin-G amorphous formulation were investigated using a computational approach. The CBZ/Rutin-G amorphous formulation was obtained via molecular dynamics (MD) simulation, which mimicked the melt-quenching method. Root mean square deviation analysis revealed that the translational motion of CBZ during the cooling process was suppressed by adding Rutin-G. Monitoring the atomic distance during the cooling process revealed that hydrogen bonds via carboxamide oxygen of CBZ with hydroxyl hydrogen of Rutin-G were preferentially formed with flavonol skeletons than sugar groups. The simulated amorphous formulation was then calculated using fragment molecular orbital (FMO) method. The quantitative evaluation of multiple interactions revealed that the hydrogen bond energy was higher in CBZ-sugar groups than in CBZ-flavonol skeleton, while the π-type of interaction energy was higher in CBZ-flavonol skeleton than in CBZ-sugar groups. The computational approach combining MD simulation and FMO calculation provides information on various interactions that are difficult to detect using experimental approaches, which helps understand the formation and stabilization mechanism of amorphous formulations.

Enhancing Dissolution Rate and Antibacterial Efficiency of Azithromycin through Drug-Drug Cocrystals with Paracetamol

Cocrystallization is a promising approach to alter physicochemical properties of active pharmaceutical ingredients (hereafter abbreviated as APIs) bearing poor profile. Nowadays pharmaceutical industries are focused on preparing drug-drug cocrystals of APIs that are often prescribed in combination therapies by physicians. Physicians normally prescribe antibiotic with an analgesic/antipyretic drug to combat several ailments in a better and more efficient way. In this work, azithromycin (AZT) and paracetamol (PCM) cocrystals were prepared in 1:1 molar ratio using slow solvent evaporation method. The cocrystals were characterized by Fourier transform infrared (FTIR), Raman spectroscopy, powder X-ray diffraction (PXRD), differential scanning calorimeter (DSC), thermo gravimetric analysis (TGA) and high-performance liquid chromatography (HPLC). Vibrational spectroscopy and DSC confirmed that both APIs interact physically and showed chemical compatibility, while PXRD pattern of the starting material and products revealed that cocrystal have in a unique crystalline phase. The degree of hydration was confirmed by TGA analysis and result indicates monohydrate cocrystal formation. The HPLC analysis confirmed equimolar ratio of AZT:PCM in the cocrystal. The in vitro dissolution rate, saturation solubility, and antimicrobial activity were evaluated for AZT dihydrate and the resulting cocrystals. The cocrystals exhibited better dissolution rate, solubility and enhanced biological activities.

Pharmaceutical cocrystals: A review of preparations, physicochemical properties and applications

Pharmaceutical cocrystals are multicomponent systems in which at least one component is an active pharmaceutical ingredient and the others are pharmaceutically acceptable ingredients. Cocrystallization of a drug substance with a coformer is a promising and emerging approach to improve the performance of pharmaceuticals, such as solubility, dissolution profile, pharmacokinetics and stability. This review article presents a comprehensive overview of pharmaceutical cocrystals, including preparation methods, physicochemical properties, and applications. Furthermore, some examples of drug cocrystals are highlighted to illustrate the effect of crystal structures on the various aspects of active pharmaceutical ingredients, such as physical stability, chemical stability, mechanical properties, optical properties, bioavailability, sustained release and therapeutic effect. This review will provide guidance for more efficient design and manufacture of pharmaceutical cocrystals with desired physicochemical properties and applications.

Pulmonary Drug Delivery of Antimicrobials and Anticancer Drugs Using Solid Dispersions

It is well established that currently available inhaled drug formulations are associated with extremely low lung deposition. Currently available technologies alleviate this low deposition problem via mixing the drug with inert larger particles, such as lactose monohydrate. Those inert particles are retained in the inhalation device or impacted in the throat and swallowed, allowing the smaller drug particles to continue their journey towards the lungs. While this seems like a practical approach, in some formulations, the ratio between the carrier to drug particles can be as much as 30 to 1. This limitation becomes more critical when treating lung conditions that inherently require large doses of the drug, such as antibiotics and antivirals that treat lung infections and anticancer drugs. The focus of this review article is to review the recent advancements in carrier free technologies that are based on coamorphous solid dispersions and cocrystals that can improve flow properties, and help with delivering larger doses of the drug to the lungs.

An industrial perspective on co-crystals: Screening, identification and development of the less utilised solid form in drug discovery and development

Active pharmaceutical ingredients are commonly marketed as a solid form due to ease of transport, storage and administration. In the design of a drug formulation, the selection of the solid form is incredibly important and is traditionally based on what polymorphs, hydrates or salts are available for that compound. Co-crystals, another potential solid form available, are currently not as readily considered as a viable solid form for the development process. Even though co-crystals are gaining an ever-increasing level of interest within the pharmaceutical community, their acceptance and application is still not as standard as other solid forms such as the ubiquitous pharmaceutical salt and stabilised amorphous formulations. Presented in this chapter is information that would allow for a co-crystal screen to be planned and conducted as well as scaled up using solution and mechanochemistry based methods commonly employed in both the literature and industry. Also presented are methods for identifying the formation of a co-crystal using a variety of analytical techniques as well as the importance of confirming the formation of co-crystals from a legal perspective and demonstrating the legal precedent by looking at co-crystalline products already on the market. The benefits of co-crystals have been well established, and presented in this chapter are a selection of examples which best exemplify their potential. The goal of this chapter is to increase the understanding of co-crystals and how they may be successfully exploited in early stage development.

A Drug-Drug Cocrystal of Dihydromyricetin and Pentoxifylline

Drug-drug cocrystals, which can regulate physicochemical properties of individual drugs and might produce synergistic therapeutic effects, have drawn growing interest in the pharmaceutical industry. In this study, a novel drug-drug (1:1) cocrystal hydrate of slightly water-soluble dihydromyricetin (DMY) and highly water-soluble pentoxifylline (PTX), DMY-PTX•H₂O (1), was prepared by a slurry method. The single-crystal X-ray diffraction results reveal that the cocrystal is formed through hydrogen-bonding interactions between hydroxyl groups of DMY and four acceptors of PTX. The dynamic vapour sorption results indicate that the cocrystal displays reduced hydrophilicity compared with DMY. It is found that cocrystal formation narrows the solubility difference between two parent drugs. The equilibrium solubility of PTX decreases greatly, while that of DMY increases slightly. As a result, DMY and PTX are synchronously and sustainedly released from the cocrystal. Further, a synergistic anti-cancer effect of the cocrystal DMY-PTX•H₂O (1) on HepG2 cells in vitro at a drug concentration of 100 μM was discovered. This study brings evidence of cocrystallization as a successful approach for synchronous sustained-release of two drugs with substantially different aqueous solubility.

Challenges and opportunities of pharmaceutical cocrystals: a focused review on non-steroidal anti-inflammatory drugs

The focus of the review is to discuss the relevant and essential aspects of pharmaceutical cocrystals in both academia and industry with an emphasis on non-steroidal anti-inflammatory drugs (NSAIDs). Although cocrystals have been prepared for a plethora of drugs, NSAID cocrystals are focused due to their humongous application in different fields of medication such as antipyretic, anti-inflammatory, analgesic, antiplatelet, antitumor, and anti-carcinogenic drugs. The highlights of the review are (a) background of cocrystals and other solid forms of an active pharmaceutical ingredient (API) based on the principles of crystal engineering, (b) why cocrystals are an excellent opportunity in the pharma industry, (c) common methods of preparation of cocrystals from the lab scale to bulk quantity, (d) some latest case studies of NSAIDs which have shown better physicochemical properties for example; mechanical properties (tabletability), hydration, solubility, bioavailability, and permeability, and (e) latest guidelines of the US FDA and EMA opening new opportunities and challenges.

The role of 3-OH in the self-assembly of pharmaceutical cocrystals of dihydroflavonol with 4,4′-bipyridine

The 3-OH group of nonplanar dihydroflavonols participates in the formation of hydrogen bonds with BPY, thereby forming cocrystals with different structures.

Cocrystallization of axitinib with carboxylic acids: preparation, crystal structures and dissolution behavior

Three cocrystals of axitinib were prepared, and they demonstrated a significantly improved apparent solubility and dissolution rate without compromising physical stability.

Cocrystal engineering of pharmaceutical solids: therapeutic potential and challenges

This highlight presents an overview of pharmaceutical cocrystal production and its potential in reviving problematic properties of drugs in different dosage forms. The challenges and future outlook of its translational development are discussed.

Cocrystallization: Cutting Edge Tool for Physicochemical Modulation of Active Pharmaceutical Ingredients

Cocrystallization is a widely accepted and clinically relevant technique that has prospered very well over the past decades to potentially modify the physicochemical properties of existing active pharmaceutic ingredients (APIs) without compromising their therapeutic benefits. Over time, it has become an integral part of the pre-formulation stage of drug development because of its ability to yield cocrystals with improved properties in a way that other traditional methods cannot easily achieve. Cocrystals are solid crystalline materials composed of two or more than two molecules which are non-covalently bonded in the same crystal lattice. Due to the continuous efforts of pharmaceutical scientists and crystal engineers, today cocrystals have emerged as a cutting edge tool to modulate poor physicochemical properties of APIs such as solubility, permeability, bioavailability, improving poor mechanical properties and taste masking. The success of cocrystals can be traced back by looking at the number of products that are getting regulatory approval. At present, many cocrystals have obtained regulatory approval and they successfully made into the market place followed by a fair number of cocrystals that are currently in the clinical phases. Considering all these facts about cocrystals, the formulation scientists have been inspired to undertake more relevant research to extract out maximum benefits. Here in this review cocrystallization technique will be discussed in detail with respect to its background, different synthesis approaches, synthesis mechanism, application and improvements in drug delivery systems and its regulatory perspective.

Drug-drug cocrystals: Opportunities and challenges

Recently, drug-drug cocrystal attracts more and more attention. It offers a low risk, low-cost but high reward route to new and better medicines and could improve the physiochemical and biopharmaceutical properties of a medicine by addition of a suitable therapeutically effective component without any chemical modification. Having so many advantages, to date, the reported drug-drug cocrystals are rare. Here we review the drug-drug cocrystals that reported in last decade and shed light on the opportunities and challenges for the development of drug-drug cocrystals.

The Role of Cocrystallization-Mediated Altered Crystallographic Properties on the Tabletability of Rivaroxaban and Malonic Acid

The present work aims to understand the crystallographic basis of the mechanical behavior of rivaroxaban-malonic acid cocrystal (RIV-MAL Co) in comparison to its parent constituents, i.e., rivaroxaban (RIV) and malonic acid (MAL). The mechanical behavior was evaluated at the bulk level by performing “out of die” bulk compaction and at the particle level by nanoindentation. The tabletability order for the three solids was MAL < RIV < RIV-MAL Co. MAL demonstrated “lower” tabletability because of its lower plasticity, despite it having reasonably good bonding strength (BS). The absence of a slip plane and “intermediate” BS contributed to this behavior. The “intermediate” tabletability of RIV was primarily attributed to the differential surface topologies of the slip planes. The presence of a primary slip plane (0 1 1) with flat-layered topology can favor the plastic deformation of RIV, whereas the corrugated topology of secondary slip planes (1 0 2) could adversely affect the plasticity. In addition, the higher elastic recovery of RIV crystal also contributed to its tabletability. The significantly “higher” tabletability of RIV-MAL Co among the three molecular solids was the result of its higher plasticity and BS. Flat-layered topology slip across the (0 0 1) plane, the higher degree of intermolecular interactions, and the larger separation between adjacent crystallographic layers contributed to improved mechanical behavior of RIV-MAL Co. Interestingly, a particle level deformation parameter H/E (i.e., ratio of mechanical hardness H to elastic modulus E) was found to inversely correlate with a bulk level deformation parameter σ₀ (i.e., tensile strength at zero porosity). The present study highlighted the role of cocrystal crystallographic properties in improving the tabletability of materials.

The Anti-Breast Cancer Effect and Mechanism of Glimepiride-Metformin Adduct

Background

Compound adduct is a eutectic crystal formed by non-covalent bonds of two compounds or multiple compounds with water. Emerging evidence suggests that adduct could be different from the simple physical mixture of the individual compounds and has some new features. Recent studies reported that both glimepiride (Gli) and metformin (Met) may possess an anti-breast cancer effect besides anti-diabetic effect. In the current study, we synthesized glimepiride-metformin adduct (GMA) and examined its anti-breast cancer effect in vitro and in vivo to explore its potential in treatment of breast cancer in diabetic patients.

Methods

GMA was synthesized from Gli, Met and water at a molar molecular mass of 1:1:1 and identified by infrared spectroscopy. MTT assay, colony formation assay and wound healing assay were performed to examine the effects of GMA on cell viability and migration of human breast cancer cell lines CAL-148, MDA-MB-453, MDA-MB-231and MCF-7. The effect of GMA on cell cycle and apoptosis was examined by flow cytometry. The orthotopic implantation model was established to observe the inhibitory effect of GMA on tumor growth. The expression of Ki67 was detected by immunohistochemistry. RT-qPCR and Western blotting were performed to investigate mechanisms for the function of GMA.

Results

Both MTT and colony formation assays showed that GMA inhibited breast cancer cell viability, and the effect was greater than Gli alone, Met alone and the combination. In vivo study showed that GMA had an inhibitory effect on tumor growth of CAL-148 xenografts. Flow cytometry analysis indicated that GMA induced G1/S phase cell cycle arrest and apoptosis in breast cancer cells. RT-qPCR and Western blotting analyses showed that GMA activated AMPK, and up-regulated expression of p53 and p21, and down-regulated expression of cyclin D1 and CDK4.

Conclusion

GMA suppresses cell viability of breast cancer cells, and its effect is greater than Gli and Met alone or combination at the same concentration. GMA inhibits breast cancer cell growth in vivo. The antitumor effect of GMA may be related to the activation of AMPK resulting in up-regulation of p53 and p21 and down-regulation of cyclin D1 and CDK4.

Polymorphs of DP-VPA Solid Solutions and Their Physicochemical Properties

Different solid forms possess various physicochemical properties, which can significantly affect the stability, bioavailability, and manufacturability of the final product. DP-VPA, a complex of 1-stearoyl-2-valproyl-sn-glycero-3-phosphatidylcholine (DP-VPA-C₁₈) and 1-palmitoyl-2-valproyl-sn-glycero-3-phosphatidylcholine (DP-VPA-C₁₆), is currently under development as an antiepileptic drug. DP-VPA-C₁₆ and DP-VPA-C₁₈ crystallize together in solid solution forms. The solid forms of DP-VPA solid solution were studied herein. Powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), dynamic vapor sorption (DVS) and optical microscopy were used to characterize the different crystalline forms, known as polymorphs. The physicochemical properties, including hygroscopicity, thermodynamic behavior, and relative stability, of each form were investigated. DVS analysis showed that DP-VPA solid solution reduced the hygroscopicity of DP-VPA-C₁₆. The relative humidity stability study revealed that Forms A and B are relatively stable, while Forms A-1, B-1, C and D are highly unstable under natural humidity. Further analysis revealed that Form A transforms into Form B through milling. Given the physicochemical properties of the available physical forms, Form B may be the optimal form for the formulation and development of antiepileptic drugs.

A novel crystal form of metacetamol: the first example of a hydrated form

We report the crystal structure and crystallization conditions of a first hydrated form of metacetamol (a hemihydrate), C₈H₉NO₂·0.5H₂O. It crystallizes from metacetamol-saturated 1:1 (v/v) water-ethanol solutions in a monoclinic structure (space group P2₁/n) and contains eight metacetamol and four water molecules per unit cell. The conformations of the molecules are the same as in polymorph II of metacetamol, which ensures the formation of hydrogen-bonded dimers and R₂²(16) ring motifs in its crystal structure similar to those in polymorph II. Unlike in form II, however, these dimers in the hemihydrate are connected through water molecules into infinite hydrogen-bonded molecular chains. Different chains are linked to each other by metacetamol-water and metacetamol-metacetamol hydrogen bonds, the latter type being also present in polymorph I. The overall noncovalent network of the hemihydrate is well developed and several types of hydrogen bonds are responsible for its formation.

Comparative Evaluation of the Photostability of Carbamazepine Polymorphs and Cocrystals

Carbamazepine (CBZ), a widely used antiepileptic, is known to be sensitive to light. The aim of this study was to evaluate the photostabilities of three cocrystals of CBZ (CBZ–succinic acid (SUC), CBZ–saccharin (SAC) form I, and CBZ–SAC form II) illuminated with a D65 fluorescent lamp compared with those of the conventional solid forms: CBZ polymorphs (forms I, II, and III). The order of discoloration determined using a colorimetric measurement was almost consistent with that of the degradation rates estimated using Fourier-transform infrared reflection–absorption spectroscopy, and these parameters of CBZ polymorphs increased in the order of form III, form I, and form II. CBZ–SUC and CBZ–SAC form I significantly suppressed the discoloration and degradation of CBZ compared with the raw CBZ, while CBZ–SAC form II facilitated the discoloration and degradation of CBZ. These results were supported by the results from the low-frequency Raman spectroscopy. The molecular mobility estimated using solid-state nuclear magnetic resonance 1H spin–lattice relaxation time strongly correlated with the degradation rate constant, indicating that molecular mobility significantly decreased following the formation of CBZ–SUC and CBZ–SAC form I and resulted in higher photostability. Overall, CBZ–SUC and CBZ–SAC form I are photostable forms and cocrystallization was proven to be an effective approach to improving the photostability of a photolabile drug.